Slurry explosive compositions containing n,n&#39; - dinitrosopentamethylenetetramine as density control agent

ABSTRACT

A SLURRY EXPLOSIVE COMPOSITION COMPRISING AT LEAST ONE INORGANIC OXYGEN-SUPPLYING SALT, A SOLVENT, A THICKENER, A FUEL AND AS A DENSITY CONTROL AGENT, N,N&#39;&#39;-DINITROSOPENTAMETHYLENETETRAMINE.

United States Patent Int. Cl. C0615 3/06 US. Cl. 149-30 12 ClaimsABSTRACT OF THE DISCLOSURE A slurry explosive composition comprising atleast one inorganic oxygen-supplying salt, a solvent, a thickener, afuel and as a density control agent,N,N-dinitrosopentamethylenetetramine.

This invention relates to slurry explosive compositions comprising a gasblowing agent for adjustment of the density to improve theirsensitivity. The invention also relates to a method of manufacturingsuch explosives.

Explosive compositions comprising an oxygen-supplying salt, for exampleammonium nitrate, and a sensitiser and/or fuel together with a fluidsolvent, disperser or carrier such as water, are known. Thesecompositions are commonly referred to as slurry explosive compositionsor, more generally, as slurry explosives. Such slurry explosives mayrange in degree of firmness or consistency from highly viscous,plastic-like extrudable compositions to less viscous, pumpable orpourable fluid-like mixtures.

Slurry explosive compositions of the aforementioned types normallycontain as essential ingredients widely known sensitising andpower-enhancing materials and fuels, for example finely divided lightmetal or finely divided carbon. In some cases it is advantageous to adda self-explosive ingredient such as particulate trinitrotoluene (TNT),pentaerythritol tetranitrate (PETN) or smokeless powder to furtherimprove the sensitivity or strength or both of the slurry explosives andthereby ensure detonation and propagation. Generally, the oxygen balanceof the total composition is within the range +15 to -35 g. of oxygen per100 g. of finished explosive. A wide range of such compositions is knownto the art.

It is well known in the art that the sensitivity of slurry explosivesmay be controlled by controlling their densities. Further, controlledvariations in density without any major change in a formulation areadvantageous under certain conditions in achieving optimum blastingresults. A number of density lowering agents and methods of aeration arealready known in the art, but the reduced density eifected thereby is,in general, not maintained over prolonged storage.

It is an object of this invention to provide a means of controlling thesensitivity of slurry explosives and to provide slurry explosives whichwill maintain their sensitivity on storage.

It has now been found that the density and sensitivity of slurryexplosives can be advantageously controlled by incorporatingN,N'-dinitrosopentamethylenetetramine in the composition. The explosivesmaintain their sensitivity over long storage periods.

Thus, in accordance with this invention a slurry explosive compositioncomprises at least one inorganic oxygen-supplying salt, a solvent forthe said salt, a thickener [for the solution of the said salt in thesaid solvent, a fuel and, as a density control agent,N,N'-dinitrosopentamethylenetetramine.

Preferably the N,N-dinitrosopentamethylenetetramine is present in anamount in the range 0.01 to 1% by weight of the composition.

3,748,200 Patented July 24, 1973 'ice Preferred slurry explosivecompositions of the invention contain 15 to 83% by weight of at leastone inorganic oxygen-supplying salt, 10 to 30% by weight of solvent, 0.2to 2.5% by weight of thickener, 5 to 55% by weight of fuel and 0.01 to1% by weight of N,N'-dinitrosopentamethylenetetramine.

The density of the composition. can be varied over a wide range byvarying the proportion of the N,N'-dinitrosopentamethylenetetramine,only a small proportion being required for a substantial reduction indensity.

The inorganic oxygen-supplying salt may conveniently comprise a nitrateof ammonia, sodium, potassium, barium or calcium or a mixture of two ormore of said nitrates,

The solvent preferably comprises water, formamide, dimethylsulphoxide,ethylene glycol or. mixtures thereof.

The fuel may conveniently comprise particulate light metal or metalloid,[for example, finely divided aluminium, aluminium alloy, silicon,ferrosilicon, ferrophosphorus, particulate organic explosive, organicnitrate, for example isopropylnitrate, sulphur, or carbonaceousmaterial, for example, carbon, urea, 'thiourea or sugar or a mixturethereof. 7

Useful particulate organic explosives which may be used in thecompositions include, for example, TNT, PETN,cyclotrimethylenetrinitramine (RDX), Composition B (mixture of TNT andRDX), Pentolite (mixture of PETN and TNT), smokeless powder,nitrocellulose, nitrostarch and mixtures of these.

In aqueous slurry explosive compositions the thickener may convenientlycomprise mannogalactans, for example guar gum or carob seed gum. Wheredimethylsulphoxide or formamide is employed alone as the solvent,hydroxyethyl cellulose may be used as the thickener. Wheredimethylsulphoxide is used in combination with water, guar gum, tamarindflour or starch are suitable thickeners.

The composition may also advantageously comprise cross-linking agents tocross-link the thickener. Suitable cross-linking agents for thepolysaccharides in aqueous slurry compositions include pentavalentantimony compounds, for example potassium pyroantimonate, or metallicchromates and dichromates, for example zinc chromate, sodium dichromateor potassium dichromate, advantageously in conjunction with a solubleantimony com pound, for example potassium antimony tartrate.

Other additional ingredients commonly used in explosive compositions,for example stabilisers, may be included in the composition as desired.

The invention also includes a method of preparing a slurry explosivewherein N,N' dinitrosopentamethylenetetramine is mixed into an acidicslurry explosive composition as a density control agent. The rate ofreduction of density by the said aerating agent can be controlled by thepH of the slurry explosive. The lower the pH, the higher is the rate ofreduction of density, but the eventual extent of density reductiondepends only upon the quantity of N,N'-dinitrosopentamethylenetetramineused. The pH is preferably in the range 3 to 6 and more preferably inthe range 4.5 to 5.5.

The composition may, for example, be acidified by zinc nitrate or if thepH is already undesirably low it may, for example, be raised by ammoniumhydroxide or an amine.

The invention is further illustrated by the following examples in whichall parts and percentages are by weight. Examples 1, 3, 6 and 8 containno N,N'-dinitrosopenta methylenetetramine and were included forcomparison.

EXAMPLES In these examples the following mixing procedure was adopted.

The oxygen supplying salt, solvent and fuel were mixed in a ribbon m1xertill a homogeneous solution or suspension was obtained. The pH of themixture was adjusted as described by addition of zinc nitrate orammonium hydroxide. Guar gum predispersed in ethylene glycol was thenadded to the mixture and mixed until a thick gel was obtained. Therequisite quantity of N,N'-dinitropentamethylenetetramine (as sold underthe trade name Vulcacel BN by Imperial Chemical Industries Limited),crosslinking agent and stabilisers were then added and mixed till ahomogeneous mix was obtained.

The sensitivity of the slurry explosive compositions was tested bydetermining the minimum charge of a series of test explosive chargesrequired to initiate detonation in 12 inch long cartridges of thecompositions having the diameter indicated. The test explosive chargesin ascending order of strength were:

No. 6 Detonator: 0.3 g. PETN base charge No. 8 Detonator: 0.5 g. PETNbase charge Anstart: 1.5 g. PETN charge Pentolite primer: 10 g.Pentolite (50/50 PETN/TNT) The density was measured as the bulk density.

Details of the compositions and properties are given in the followingtables:

Table 1 shows the effect of incorporation of various proportions ofN,N-dinitrosopentamethylenetetramine on density and sensitivity of twocompositions containing no self explosive sensitiser.

Table 2 shows the efiect of incorporation of N,N'--dinitrosopentamethylenetetramine on density and sensitivity of acomposition containing a self explosive sensitiser.

Table 3 shows the storage properties of three typical slurry explosivecompositions containing N,N'-dinitrosopentamethylenetetramine withoutself-explosive sensitiser.

Table 4 shows the effect of pH on the rate of reduction of density of atypical slurry explosive containing N,N'-dinitrosopentamethylenetetramine without self explosive sensitiser.

TABLE 1 Example N o- 1 2 3 4 5 Composition, percent:

Ammonium nitrate--- 56. 80 56. 68 47. 40 47. 39 46. 40 Sodium nitrate15. 15. 00 15. 00 15. 00 15. 00 Isopropyl nitrate. 10. 00 10. 00 Guargum 1. 00 1. 00 1. 00 1. 00 l. 00 Air-atomised aluminium 10. 00 10. 0010. 00 Ethylene glycol. 1. 50 1. 50 1. 50 1. 50 1. 50 Dimethylsulphoxide5. 00 00 5.00 Nitrocotton (33% moistur 0.60 0.6 Zinc chromate.. 0. 0. 100. 10 0. 10 0. 10 Vulcacel BN 0.12 0. 01 1. 00 15. 00 15. 00 20. 00 20.O0 20. 00 Water properties:

Density, g./cc. at 33 C 1.37 1.07 1.44 1.32 0.73 p 4. 6 4.8 4. 6 4. 7 4.7 Minimum initiator in 1" unconfined 1 10 g. No. 6 1 10 g. 1 10 g No 6Minimum initiator in 2" unconfined 1 10 g. No. 6 1 10 g. 1 5 g No. 6

1 Pentolite.

TABLE 2 Example No 6 7 8 Composition (percent):

Ammonium nitrate. 46. 40 46. 31 51. 40 51. 32 Sodium nitrate- 15. 00 15.00 15. 00 15. 00 5. 00 5. 00 5. 00 5.00 Isopropyl nitrate 10. 00 10. 0010. 00 10. 00 Nitrocotton (33% moisture). 0.60 0.60 0.60 0. 60 Guargum 1. 00 1. 00 1. 00 1. 00 Ethylene glycol 1. 50 1. 50 1. 50 1. 50 Zincchromate 0. 10 0. 10 0. 10 O. 10 Vulcacel BN-- 0. 0 0.08 Water 15. 0015. O0 15. 00 15. 00 Air-atomised aluminium 5.00 5.00Diethyldiphenylurea 0. 40 0. 40 0. 40 0. 40 Properties:

Density, g./cc 1. 44 1. 13 1. 40 1. 16 pH 4. 7 4. 8 4. 8 4. 9 Minimuminitiator in 1 une 1 10 g. No. 6 1 10 g. No.6 Minimum initiator in 2"unconfined l 10 g. No. 6 1 10 g. No. 6

1 Pentolite.

TABLE 3 Example N6 10 11 12 Composition, percent:

Ammonium nitrate 61. 3 46. 3 41. 3 Sodium nitrate 15. 0 15. 0 15. 0Isopropyl nitrate 6. 0 10.0 15. 0 Air-atornised aluminum- 10. 0 10. 010. 0 Nitrocotton (33% moisture)- 0. 6 0. 6 0. 6 Guar gum 1. 0 1. 0 1.0Ethylene glycol 1. 5 1. 5 1.5 Diethyldiphenylurea- 0. 4 0. 4 0. 4 Zincchromate 0.1 0.1 0. 1 Water 15. 0 15. 0 15. 0 Vulcacel BN. 0. 1 0. 1 0.1 Properties:

Fresh:

Density g.lcc 1. 18 1.18 1. 12 Minimum initiator in 1" unconfined-.- 10g. No. 8 No.6 Minimum initiator in 2 unconfined.-.- No. 6 No. 6 After 2months at 30 0.:

Density, g./cc 1. 18 1. 13 Minimuminitiator in 1" unconfiued..-- 1 10 g.N o. 23 No.11 Minimuminitiator in 2" unconfined..-- N o. 6 No. 6 After 4months at 30 0.:

Density, g./cc 1.18 1.14 1.12 Minimum initiator in 1" unconfined.-- 1 10g. No. 8 No. 6 Minimum initiator in 2 unconfined No. 6 No. 6

1 Pentolite. 1 Anstart.

EXAMPLES 13 AND 14 The composition of these examples was PercentAmmonium nitrate 56.70 Sodium nitrate 15.00 Guar gum 1.00 Ethyleneglycol 1.50 Isopropyl nitrate 10.00 Nitrocotton (33 moisture) 0.60 Zincchromate 0.10 Vulcacel BN 0.10 Water 15.00

TABLE 4 Minimum initiator in Example Time, Density, N 0. pH hours g./cc.1" unconfined 2 unconfined 13 3.0 0.0 1. 37 10 g. Pento- 10 g.Pentolite. lite. 16. 0 18. 0 20. 0 24.0 14 5. 0 0. 0

What we claim is:

1. A slurry explosive composition comprising at least one inorganicnitrate, a solvent for the said inorganic nitrate, a thickener for thesolution of the said inorganic nitrate in the said solvent, a fuel and,as a density control agent N,N'-dinitrosopentamethylenetetramine.

2. A composition as claimed in claim 1 containing 15 to 83% by weight ofat least one inorganic nitrate, 10 to 30% by weight of solvent, 0.2 to2.5% by Weight of thickener, 5 to 55% by weight of fuel and 0.01 to 1%by weight of N,N'-dinitrosopentamethylenetetramine.

3. A composition as claimed in claim 1 wherein the inorganic nitrate isselected from the group consisting of the nitrates of ammonia, sodium,potassium, barium or calcium and mixtures of two or more of saidnitrates.

4. A composition as claimed in claim 1 wherein the solvent is selectedfrom the group consisting of Water, formamide, dimethylsulphoxide,ethylene glycol and mixtures thereof.

5. A composition as claimed in claim 1 wherein the fuel is selected fromthe group consisting of particulate light metal, particulate organicexplosive, organic nitrate, sulphur and carbonaceous material.

6. A composition as claimed in claim 5 wherein the fuel is selected fromthe group consisting of aluminum, aluminium alloy, silicon,ferrosilicon, ferrophosphorus, carbon, urea, thiourea, sugar, isopropylnitrate, trinitrotoluene, pentaerythritol tetranitrate,cyclotrimethylenetrinitramine, smokeless powder, nitrocellulose,nitrostarch and mixtures of two or more thereof.

7. A composition as claimed in claim 1 wherein the thickener is selectedfrom the group consisting of guar gum, carob seed gum, tamarind flour,hydroxyethyl cellulose and starch.

8. A composition as claimed in claim 1 comprising as a cross-linkingagent for the thickener, a compound selected from the group consistingof pentavalent antimony compounds, metal chromates and dichromates.

9. A composition as claimed in claim 8 wherein the cross-linking agentcomprises a compound selected from the group consisting of metallicchromates and dichromates in conjunction with a soluble antimonycompound.

10. A composition as claimed in claim 9 wherein the soluble antimonycompound is potassium antimony tartrate.

References Cited UNITED STATES PATENTS 5/1964 Gaskins et a1. i14992 X7/1965 Klager l49-92 X STEPHEN I. LECHERT, JR., Primary Examiner US. Cl.X.R.

UNITED; sTATEsvATENT' OEFIGE? QERETI MATE; -EFGTI-QN.

Patent n H Datedv J l $9.73....

Inventor(s) Bnairab Hath-Roy e1; I

It is certified that. error appears in the above-identified parent; andthat said Letters Patent are hereby corrected as shown below:

(1) In the heading, Foreign Application Priority Data shquld be added asfollows:

January 21, 1971 British 2867/71 Signed and sealed this th day ofNovember 1973.

(SEALL Attest:

EDWARD M,FLETCHER,JR. RENE D. TEGTI IEYER Attesting Officer ActingCommissioner of Patents FORM 5 o LgscoMM-oc scan-Pas UNITED STATES;PATENT" QEFKT Ei QER'HFKCATE @F QQRREQTION Patent No- 3,74,489200 DatedI July Inventor(s) Bhairab Hath ROy et al It is certified that errorappears in the above-identified paye' lt, and that said Letters Patentare hereby corrected as shown below;

(1) In the heading, Foreign A lication Priority Data shquld be added. asfollows:

-=.- January 21, 1971, British 2867/71 ed and sealed this 20th day ofNovember 1 973.

(SEAL) Attest:

EDWARD MQFLETCHERJR, RENE D. TEGTMEYER Attesting Officer ActingCommissioner of Patents

